Electronic apparatus



March 3o, 1937. B. E. LENEHAN 2,075,120

ELECTRONIC APPARATUS Filed Feb. 23, 1955 WITNESSES: INVENTOR 5eronc/fene/van.

\ BY AT NEY Patented Mar. 30, 1937 UNITED STATES PATENT OFFICEELECTRONIC APPARATUS of Pennsylvania Application February 23, 1935,Serial No. 7,929

15 Claims.

My invention relates to electronic apparatus and particularly to lightrelays as used for counting and sorting, the photoelectric control ofdoors and traiiic signals, the control of web-working machinery andsimilar applications. In its more speciiic aspects, my invention relatesto light relays of the type consisting ci a photo-responsive element,such as a photo-tube, an electronic amplifier connected to respond 'to avariation of electric condition of the photo-tube, and anelectromagnetic relay responsive to the output oi the amplifier. In itsmore general aspects, the invention provides novel features of generalutility in connection with rectifying apparatus, amplifiers and lightrelays.

In one form of light relay, as heretofore constructed, a single triodeor pentode has been used for amplification, and a voltage doubler hasbeen provided for supplying the plate voltage of this tube. Such a lightrelay is simple and compact, but for many applications, particularlyWhere the distance between the light source and phototube is great, isnot sufficiently sensitive to insure positive operation with commercialforms of light sources. If the overall amplification of the relay isincreased by adding tubes, the additional complications usually resultin a considerable sacriiice of simplicity and compactness.

It is an object of my invention to provide a novel amplifying circuitfor light relays of the type mentioned above.

Another object of my invention is to provide a novel super-sensitivelight relay.

Other objects of my invention will become evident from the followingdetailed description taken in conjunction with the accompanying drawing,in which the single figure is a diagrammatic View of a light relayembodying my in- Vention.

Referring to the drawing in detail, a suitable rectifying device Ihaving two independent anode-cathode discharge paths or rectifyingelements 4I and 42, is provided for charging a pair of condensers 2 and3. The condensers 2 and 3 each have one terminal connected to aconductor 4 of an alternating-current supply circuit, and the remainingterminal connected with an electrode of the rectiiying device i. Theremaining two electrodes of the device l connected to the remainingconductor E of the supply circuit, in a well known manner, to form avoltage doubler.

The condenser 3 is connected to supply plate voltage to a diode-triodetype vacuum tube 6. This tube preferably is of the so-called duplex-(Cl. Z50-41.5)

diode high ampliiication type, that is, is provided with a pair of diodeplates I, which cooperate with the cathode 8 of the tube to form a diodeor rectifier. The usual grid Q and plate II) are arranged to cooperatewith the cathode 8 to form a triode having a high amplification factor.

The condenser 2 is connected to supply plate voltage to a pentode I 2.The pentode I2 isk of the usual type having a cathode I3, an anode orplate I4, a control grid I5, a screen I6 interposed between the controlgrid I5 and the plate i4, and a suppressor I1, interposed between thescreen I6 and the plate I4. The screen I6 is connected to a suitablepositive source such as the positive terminal of the condenser 2, andserves the function of reducing the plate voltage required and renderingthe plate current substantially independent of plate voltage. Thesuppressor I1 is connected to the cathode I3, in the usual manner, toreduce secondary emission from the plate I4.

The three tubes I, 6 and I2 are all preferably of the sc-called hard orhighly evacuated type, and are all provided with insulated heaters 20for the cathodes. The heaters 20 are built within the cathodes in theusual manner, but, for simplicity of illustration, are shown separatefrom the tubes, and connected in a series circuit to the supplyconductors 4 and 5. A resistor 2I is provided for absorbing the excessof supply voltage above that necessary for the heaters 20.

In accordance with my invention, the diode circuit of the tube 6 isnon-conductively coupled to the alternating-current supply circuit 4, 5in such manner that an alternating-current voltage is appliedbetween thediode plates 'I and the cathode 8, but a conductive connection betweenthe cathode 8 and upper conductor 5 of the supply circuit is avoided. Tothis end, a condenser 22 and a resistor 23 are connected between thediode circuit of the tube 6, and an alternatingcurrent circuitconsisting of the condenser 3, the condenser resistor 23, and a blockingcondenser 24. The condensers 3 and 22, pass alterhating-current in theusual manner, notwithstanding that they accumulate a direct-currentcharge in the connection shown. The condenser 24 serves to prevent thecondenser 22 from discharging through the alternating-current source(not shown) when the light relay is in operation, and accordinglypermits the condenser 22 to accumulate a direct current charge, asindicated by the minus signs.

A high-resistance potentiometer consisting of @n `adjustable resistor 26and a fixed leak resistor 2l is connected across the condenser 22 forsupplying an adjustable bias to the grid S of the tube 3. A photo-tube29, which may be either or the highly exhausted or of the gaslled type,is connected to the grid 9 for controlling the potential of the latter.The phototube 29 may be connected between the grid 3 and plate lil ofthe tube G, as shown, in order to obtain relay operation when the supplyof light to the photo-tube is interrupted, or may alternatively beconnected between the resistor 21 and the grid 9, to obtain relayoperation when the photo-tube 29 is illuminated. A pair of sockets 35are permanently connected in the circuit to permit either connection.

A plate resistor 3i. of suitable resistance value, is connected in theplate circuit of the triode 6, and a condenser 32 is connected inparallel to the plate resistor 3l to provide a short time delay in theoperation of the light relay.

The plate ii) of the tube S is connected to the control grid i5 of thepentode l2, and the plate I4 of the pentode l2 is connected in serieswith a suitable electromagnetic contacter 33.

It will be noted that the mutual impedance relationship of condenser 22and resistor 23, mentioned above, leaves one degree of freedom in thedesign of these elements, inasmuch as the proper total impedance dropacross both elements in series can be secured with various relationshipsof capacitance and resistance in the elements themselves. This degree offreedom is preferably taken up in making the time constant of the gridcircuit of the triode B equal to the time constant of the plate circuitof the triode 6 for the value of plate resistance existing when thephoto-tube 23 is normally illuminated. In this way, if a sudden decreaseof line voltage occurs while the device is in operation, the biasvoltage and the plate voltage of the triode 6 decrease exponentiallywith respect to time, but maintain the same ratio to each other. Thechange of plate current of the triode 6, under these conditions isnegligible, and a false operation is avoided.

The resistors 23, 27 and 26 and the condenser 22 may be considered as asingle mutual impedance having a first terminal 36 connected to thecathode 8 and a second terminal 3'! connected to the diode plates 1. Thecondenser 3 is connected between the rst terminal 36 and a rst conductord of the supply circuit. The condenser 2li is connected between thesecond terminal 3l and a second conductor 5 of the supply circuit. andthe rectifying element 4l of rectifier i is connected between the firstterminal 35 and the second conductor The condenser 2 has a connection 32to the rst conductor 4l, and a second connection 39 to the rectifyingelement 42 of the rectiner i.

The operation of the above-described apparatus may be set forth asfollows: Upon connection of the supply conductors fl and to a suitablealternating-current source, rectified current flows through therectiiying device i, and the condensers 2 and 3 acquire direct-currentcharges in the directions indicated by the plus, zero and minus signs.The voltage developed across the two condensers 2 and 3 in series willvary from a maximum of twice the crest voltage of thealternating-current source at no load, to a considerably lower valueunder load, depending upon the load current drawn and the capacitance ofthe condensers. For a volt alternating-current source, this voltageunder ordinary load conditions may be of the order of 200 volts, forexample.

A circuit for energizing the diode elements 8 of the tube 6 from thealternating current source 4, 5, may be traced as follows: From thesupply conductor t'. through the condenser 3, thence in two parallelpaths through the condenser 22 and through the resistors 26 and 21,respectively, to the lower junction point 44; from the junction point 44as a single circuit through the resistor 23 and condenser 24 to thesupply conductor 5. The alternating voltage of the supply circuit 4, 5being impressed upon the circuit just traced, impedance voltage drops,or IZ drops, are set up in the various condensers and resistors, inaccordance with the usual laws of voltage distribution in an impedancenetwork. The impedance voltage drop appearing between the iirst terminal35 and the second terminal 3l is directly impressed upon the diodeelements l, 8 of the tube 6. because of the fact that the impedanceelements 22, 2G, 2'1 and 23 are common to both the input circuit of thediode consisting of the electrodes 'l and 3 of tube 3 and the energizingcircuit traced above. The portion of the impedance network consisting ofthe condenser 22 and resistors 23, 26 and 2i, accordingly, may beregarded as a single mutual impedance, as mentioned above. Because ofthe alternating impedance voltage drop impressed upon the diodeelectrodes 'l and 8, and because of the unidirectional conductingcharacter of the discharge space between these electrodes, a pulsatingunidirectional current ows in the diode circuit until the condenser 22is charged to the peak or crest value of the impedance drop. The chargeaccumulated by the condenser 22 in this way provides a suitable biasVoltage for the tube 6, and also a photo-tube voltage for the photo-tube23, when the latter is mounted in the lower socket 30.

It will be noted that the connection described above provides adirect-current voltage having an overall no-load maximum greater thantwice the peak value of the impressed alternating-current voltage. Thishigh direct-current voltage can be obtained between the upper terminalof condenser 2 and the lower terminal of condenser 22. it is alsopossible to obtain a rectified half wave voltage greater than the peakvalue of the impressed alternating-current voltage. This voltage may beobtained between the conductor 4 and the lower terminal of the condenser22.

In obtaining these high voltages, the condensers 3 and 2t providedirect-current insulation separating the condenser 22 from the supplycircuit e, 5. ecause of this insulation, with reference todirect-current charge, the direct current voltage accumulated on thecondenser 22 is added to the direct-current voltage on the condensers 2an S, producing a total direct-current voltage, betw en the connection39 and the junction point lill, which may be greater than twice thecrest voltage of the alternating-current supply circuit il, 5, underconditions of no-load. 1n prior art voltage dcublers and similarapparatus, so i'ar as I am aware, it has not been practical to obtainno-load direct-current voltages higher than twice the crest Value of thealternating-current voltage supply, except by the use of transformers,or equivalent.

inasmuch as the plate circuit of the pentode E2, the plate circuit ofthe triode 5 and the grid circuit of the triode 6 are supplied fromseparate condensers 2, 3 and 22 respectively, and the cou- CII pling ofthese circuits is negligible, regenerative effects in both tubes areavoided.v

Assuming that the photo-tube 29 is mounted in the upper socket 30, asshown, and is being constantly illuminated from a light-source (notshown), a photo-electric current flows through the tube 29 tending tochange the potential of the grid 9 from negative to positive. Thecircuit is preferably so designed that the grid 9 is at a potentialclose to the cut-off point of the tube S, under these circumstances. Thetube 6 accordingly passes a small plate Current which flows through theplate resistor 3|, setting up an IR drop therein which biases thecontrol grid I5 of the pentode I2 negatively. The plate current of thepentode I2 may be small or zero under these conditions.

If the supply of light to the photo-tube 29 is interrupted, the latterbecomes non-conducting, and the potential of the grid 9 becomessufficiently negative to interrupt the plate current of the tube B. Uponinterruption of the plate current of tube 6, the charge upon thecondenser 32 dissipates through the resistor 3|, and the negativevoltage of the grid I5 disappears, thereby allowing a heavy platecurrent to flow through the coil of contactor 33 to effect operation ofthe latter.

By choosing a condenser 32 of suitable capacitance, the time delay ofthe light relay may be varied as desired.

I do not intend that the present invention shall be restricted to thespecific structural details, arrangement of parts or circuit connectionsherein set forth, as various modifications thereof may be effectedwithout departing from the spirit and scope of my invention. I desire,therefore, that only such limitations shall be imposed as are indicatedin the appended claims.

I claim as my invention:

l. In apparatus for increasing and rectifying the voltage of analternating-current source, an alternating-current supply circuit havinga first conductor and a second conductor, a mutual impedance having afirst terminal and a second i terminal, a condenser connected betweensaid first conductor and said first terminal, a condenser connectedbetween said second conductor and said second terminal, and rectifyingapparatus including a pair of rectifying elements having electrodes ofopposite polarity connected to said first terminal, one of saidrectifying elements having its remaining electrode connected to saidsecond conductor, and the other of said rectifying elements having itsremaining electrode connected to said second terminal, whereby themaximum direct-current voltage available between said first conductorand said second terminal exceeds the instantaneous maximum voltage ofsaid supply circuit.

2. In apparatus for increasing and rectifying the voltage of analternating-current source, an alternating-current supply circuit, animpedance including a capacitive element, a pair of condensers, a seriescircuit connecting said con densersand said impedance to said supplycircuit, said impedance being included between said condensers, andrectifying apparatus including a rectifying element connected across atleast a part of said impedance, said part including said capacitiveelement, and a rectifying element connected across one of saidcondensers and said part, the relative direction of said rectifyingelements being such that unlike electrodes thereof 'are conductivelyconnected together at said imutual impedance.

3. In apparatus for increasing and rectifying the voltageof saidralternating-current source, an alternating-current supply circuit havinga first conductor and a second conductor, a mutual impedance having afirst' terminal and a second terminal, a condenser connected betweensaid first conductor and said first terminal, acondenser connectedbetween said second conductor and said second terminal, a condenserhaving a connection to said first conductor and having a secondconnection, and rectifying apparatus including a first rectifyingelement connected across said mutual impedance, a second rectifyingelement connected between said first terminal and said second conductor,and a third rectifying element connected between said second connectionand said second conductor, said first and second rectifying elementshaving electrodes of unlike polarity connected to said first terminal,and said second and third rectifying elements having electrodes ofunlike polarity connected to said second conductor, whereby the maximumvno-load direct-current voltage between said second terminal and saidsecond connection exceeds twice the maximum instantaneous Voltage ofsaid supply circuit.

4. The combination defined in claim 3 in which the mutual impedanceconsists at least partially of capacitance.

5. The combination defined in claim 3 in which the mutual impedanceconsists of capacitance and resistance.

6. 'I'he combination defined in claim 3 in which the rectifying elementsare of the hot-cathode type having insulated heaters, and in which theheaters are connected in a series energizing circuit.

7. In electronic apparatus energizable from an alternating-currentsource, an alternating-current supply circuit, a mutual impedance, afirst condenser, a second condenser, a series circuit connecting saidcondensers and said mutual impedance to said supply circuit, said mutualimpedance being connected between said condensers, an electric.discharge device having a rectifying discharge path and a controlleddischarge path electrically connected at their cathode ends, said deviceincluding a cathode, an anode and a control element for said controlleddischarge path and a diode plate for said rectifying discharge path, aconnection from said cathode to said series circuit at a point betweensaid mutual impedance and said first condenser, a connection from saiddiode plate to Said series circuit at a point between said mutualimpedance and said second condenser,

a connection from said mutual impedance to said .3

control element, a connection from said anode to said supply circuit onthe side thereof connected to said first condenser, a rectifier, and aconnection from said cathode to said supply circuit on the side thereofconnected to said second condenser, said last-mentioned connectionincluding said rectifier, the direction of rectification thereof beingsuch as to pass the current supply of said controlled discharge path.

8. The combination defined claim 7 in wlfnch the mutual impedanceconsists at least partially of capacitance.

9. The combination defined in claim 7 in which the mutual impedanceconsists of capacitance and resistance.

i0. The combination defined in claim 7 in which the connection from themutual impe-dance to the control element includes a high-resistancepotentiometer connected across at least part of the mutual impedance.

11. In a light relay energizable from an alternating-current source, analternating-current supply circuit including a reference conductor, avoltage doubler comprising a pair of condensers and rectifying means forcharging one of said condensers positively and the other negatively ascompared to said reference conductor, a pair of coupled amplifyingdischarge devices energized from said condensers, one of said dischargedevices having a diode discharge path, means for producing a biasingvoltage more negative than said negatively charged condenser comprisinga mutual impedance connected in parallel to said diode discharge pathand capacitance means connecting said mutual impedance in insulatedrelationship to said supply circuit, and a photo-electric element forcontrolling said amplifying discharge devices.

12. The combination defined in claim 11 in Which the amplifyingdischarge Idevice having the diode path is connected to the negativelycharged condenser and the other amplifying device is connected to thepositively charged condenser.

13. The combination dei-ined in claim 11 in which the amplifyingdischarge device having the diode path is connected to the negativelycharged condenser and the other amplifying device is connected to thepositively charged condenser, and in which the output circuit of theamplifying device having the diode path is directly coupled to the inputcircuit of the other discharge device.

14. 'I'he combination defined in claim 11 ln which the amplifying devicehaving the diode path is of the diode-triode type, and the remainingamplifying device is a pentode.

15. In a direct-coupled amplifying unit energizable from analternating-current source, a rst-stage electronic device having acathode, an anode and a control electrode, a second-stage amplifyingdevice having a cathode, an anode and a control electrode,direct-current supply means for said devices comprising a firstterminal, a second terminal, a third terminal, a fourth terminal andrectifier and condenser means energized from said source for maintainingprogressively more negative direct-current voltages on said rst, second,third and fourth terminals, means connecting said rst terminal to saidanode of said second-stage device, a direct connection of minimumimpe-dance from said second terminal to the cathode of said second-stagedevice, a direct connection of minimum impedance from said thirdterminal to the cathode of said first-stage device, a comparativelyhigh-resistance coupling circuit connecting said second terminal to saidanode of said rst-stage device, a connection from said coupling circuitto said control electro-de of said second-stage device and a connectionfrom said fourth terminal to said control electrode of said first-stagedevice, whereby regenerative effects in said devices are substantiallyavoided.

BERNARD E. LENEHAN.

